The sleek green pay toilet in San Francisco's Civic Center Plaza, next to a children's playground and across from the main library, wasn't working last week.

The digital readout on the high-tech, self-cleaning commode said "Occupied. " But it wasn't.

"You want to get in? I can get you in," shouted a hefty woman walking toward one of the 23 French-made pay toilets sprinkled throughout the city.

She body slammed it. With a single heave from her left shoulder, the shining silver door slid wide open.

"It never works. But if you hit the door, it always opens," said the 49- year-old woman, who declined to give her name but announced that she was a crack addict and needed the rest room right then for a fix.

Six years after then-Mayor Frank Jordan sat inside the city's first JCDecaux Co. toilet for its debut, about 25 percent of the new street toilets have become major problems for maintenance crews, police and tourists who try to use them.

Three toilets are so bad the Police Department asked JCDecaux to close them at night starting this spring, according to company officials, despite their contract with the city to keep the toilets open 24 hours a day.

Company representatives consider vandalism and illegal activity the price of doing business. They anticipated these problems, especially in San Francisco's neighborhoods where the homeless traditionally congregate.

"Anything that has contact with the public is going to have maintenance," said the company's local general manager, Stephen Whitlock.

Whitlock added: "We're not the police force. We are a maintenance company. We maintain the toilets to the best of our ability."

The city, too, believes the free toilet program generally is positive for residents and tourists alike despite the problems.

The roomy 84-square-foot rest rooms, costing about $150,000 each, were provided without cost to the city in 1995 in exchange for the right to sell advertising space on 90 matching JCDecaux kiosks.

San Francisco was the first city in the United States to install these automated facilities. The city now has 23 with two more under construction. Palo Alto has two, San Jose has seven, and Los Angeles is considering installing them.

For 25 cents (or a free token that San Francisco distributes to the homeless), the bathroom door slides open and shut automatically, the toilet cleans and disinfects itself after each use, and the sink senses the presence of a customer's hands and dispenses soap, warm water and hot air.

JCDecaux technicians visit all the toilets at least once a day and file maintenance records with the city.

Those records reveal the best and the worst of the public lavatories.

The best, generally, are in tourist areas, such as Union Street at Columbus Avenue and along the Embarcadero, where the concrete walls and floors are clean and fresh smelling.

The worst are in Civic Center Plaza and outside the Mission Street BART stations at 16th and 24th streets, areas known as hangouts for the homeless, drug dealers and prostitutes.

A recent peek inside the 16th Street rest room revealed a floor littered with orange plastic caps from hypodermic needles and condom wrappers. Another problem toilet at Larkin and Myrtle streets just spit out coins and refused to open.

"I think they are better looking than your average public facility," said Laurie Armstrong, the bureau's vice president of public relations.

Tourists Gary and Millie Hendrix, visiting last week from Arizona, found the toilets quite convenient.

"I've never seen anything like this," Gary Hendrix, 55, said as he stepped out of a clean commode at Fisherman's Wharf.

"I think they are kind of neat," said Millie Hendrix, 51.

Still, tourists can bump up against the seedy side of San Francisco at the pay facilities. Records show JCDecaux technicians shoo sleeping homeless men many mornings out of the toilets at Fisherman's Wharf and at the cable car turnaround on Market at Powell streets.

They manage to spend the night inside even though one quarter supposedly gives you only 20 minutes of privacy before the door slides open. If the door is jammed closed, or any other problem is detected by the computerized bathroom, a red light flashes at JCDecaux's San Francisco office.

But JCDecaux technicians go off duty at 9 p.m., Whitlock said.

FREQUENT BREAKDOWNS

At Justin Herman Plaza, a popular tourist spot across from the historic Ferry Building, even the homeless who occasionally camp there complain the toilet frequently breaks down.

"Most of the time, they don't work," said Tad Sky, who has been selling jewelry at the open-air market at the plaza for nearly 20 years.

Sometimes the door is stuck open or shut or the display simply says out of service, Sky said. He has found needles and bloody rags inside.

"It's much better to have a public toilet than not, but when it's not working, I have to send people into the hotel," he said, pointing to the nearby Hyatt Regency. "It's just not right for all the tourists."

Szeto of the Public Works Department said he expected maintenance problems, but was surprised to learn some toilets were closed at night.

"It's better than nothing there at all, but it bothers me that a lot of these may not be working," said Szeto, who plans now to take a closer look at JCDecaux's maintenance.

The police are not surprised by the problems surrounding the toilets. Officers in the Tenderloin District are even trained how to break in if they need to.

In 1999, the toilets were unwitting co-stars in an HBO documentary about heroin use in San Francisco. A Berkeley filmmaker followed a group of strung- out junkies into the pay toilets, where they used their 20 minutes to shoot up.

CAUGHT IN THE MIDDLE

"We predicted there would be some problems," said police spokesman Sherman Ackerson. "But we're sort of between a rock and a hard spot. San Francisco needs these public toilets. A lot of street people were not using facilities before."

As for the criminal elements surrounding certain toilets, Ackerson said, "It's something people should be aware of."